Jeffrey Murawsky, healthcare chief for the VA's Chicago-based regional office, was nominated last month to be the department's new undersecretary for healthcare, replacing Robert Petzel, who resigned under pressure. Petzel had been scheduled to retire later this year but was asked to leave early amid a firestorm over delays in patient care and preventable deaths at veterans hospitals.

Murawsky now oversees seven VA hospitals and 30 clinics in Illinois, Indiana, Wisconsin and Michigan, including one in suburban Chicago where there are allegations that its staff used secret lists to conceal long patient wait times for appointments. Murawsky was a doctor at the Hines, Illinois, hospital and technically remains on staff.

The White House said in a statement that Murawsky feared a prolonged fight over his confirmation, adding that he believes the role is too important not to be filled quickly.

Obama accepted Murawsky's withdrawal and will move quickly to find a replacement, the White House statement said. The VA is required by law to convene a commission to seek and review candidates for the position, which oversees the 9 Veterans Health Administration, the largest single health provider in the nation with 9 million patients, 150 hospitals and 820 walk-in clinics.

Robert Jesse, Petzel's chief deputy, has served as acting undersecretary since Petzel resigned May 16.

Meanwhile, acting VA Secretary Sloan Gibson was making a visit Thursday to the Phoenix VA medical center, where reports about veterans dying while awaiting appointments set off the furor resulting in retired Gen. Eric Shinseki's resignation last week after holding the top VA job in Obama's Cabinet the past five years.

An interim inspector general's report last month said veterans in Phoenix wait an average 115 days for a first appointment — five times longer than the 24-day average the hospital had reported. The inspector general said more than VA facilities nationwide were under investigation.

The VA said in a statement Thursday that officials appreciate Murawsky's service to veterans and respect his request to withdraw his nomination.

Murawsky's withdrawal comes as the Senate moves forward on a compromise bill to help veterans avoid long waits to see a doctor and make it easier to fire administrators who falsify records to cover up long wait times.

Hopes for a vote this week were dashed, but senators said they would press ahead on a measure to address an uproar over veterans' healthcare following allegations that veterans have died while waiting to see a Veterans Affairs doctor.

Senators had wanted to pass the bill before Friday's 70th anniversary of the Allied invasion of Europe in World War II. As many as a dozen senators were expected to attend the D-Day ceremonies in France.

Sen. Bernie Sanders, I-Vt., chairman of the Senate Veterans Affairs Committee, had said Wednesday he was "cautiously optimistic" that a vote could be held Thursday.

Sanders and Republican Sen. John McCain of Arizona were leading negotiations on the bill, holding two closed-door meetings Wednesday to iron out details. The senators met again Thursday.

The main stumbling block appeared to be when and under which circumstances veterans could turn to doctors and other providers outside the 1,700-facility VA system for what is largely free care for them.

The two lead negotiators couldn't agree on how to define it. Sanders said the primary issue was waiting times, while McCain said it was giving veterans a choice beyond the VA for receiving care.

A bill sponsored by Sanders would allow veterans who can't get timely appointments with VA doctors to go to community health centers, military hospitals or private doctors.

McCain would rather let veterans who can't get a VA appointment within 30 days or who live more than 40 miles from a VA hospital or clinic go to any doctor who participates in Medicare or the military's TRICARE program.